Bushing terminal guard



May 17, 1960 M. BROVERMAN BUSHING TERMINAL GUARD Filed Dec. 20, 1955127751 75," N/c/me/Brm ermaq, 39 WW His flllfirn y. I

' BUSHING TERMINAL GUARD Michael. Broverman, Pittsfield, Mass, assignorto General Electric Company, a corporation of New York ApplicationDecember 20, 1955, Serial No. 554,178

2 Claims. (Cl. 339-.-Z02) This invention relates to a bushing terminalguard, and morev particularly, to a protective cap for the terminalclamp and terminal end of an electrical terminal bushing,

, In my copencling patent application Serial No. 554,170, entitled.Bushing Terminal Guard, filed December 20, 1955, and now Patent Number2,834,829 and assigned tothe same assignee as the instant case, isdisclosed a protective cap for the terminal end of an electricalterminal bushing which substantially completely encloses saidterminalend as Well as the terminal clamp hardware. Additionally, meansis provided for securely fastening the cap with respect to said terminalend and said terminal clamp hardware. Said means does not depend for itsoperation on elastic snapping on of the cap with. respect to the bushingwhich means that the cap need not necessarily be constructed fromelastic compositions which may have poor weathering characteristics.

Also, in said copending patent application the arrangement isv suchwhereby the lead connected to the terminal clamp leaves the terminalclamp vertically through the upper end of the cap instead ofhorizontally through a side wall of, the cap. A vertical take oil of thelead from the clamp provides better bird or other, animal proofing ofthe electrical installation than a horizontal take ofi. For instance,the terminal bushing may be vertically mounted on the top cover of thegrounded main tank of an electrical apparatus such as a transformer.With a horizontal take off. of the lead, which may be completely bare ofelectrical insulation, there is greater likelihood that a bird or otheranimal standing on the cover will reach the lead and short circuit theapparatus to ground even though'the terminal end of the bushing andterminal clamp may be protected by aninsulating cap.

It" is an object of the instant invention to provide a bushing terminalguard which will have all the heretofore discussed advantages of mycopending invention as well as the further advantage of an electricallyinsulated operating knob for the guarded terminal clamp.

In my copending invention the cap; is first slipped on the. lead, thenthe lead is connectedto the clamp while the cap is held in a raisedposition, and then the cap is lowered along the lead toward the upperterminal end of the bushing for fastening with respect to said terminalend and said clamp. This means that the cap cannot be shipped in itsfinal-assembled position, orif it is, it must be removed to clamp thelead. By contrast, in the instant invention the cap can be shipped inits final assembled position and the lead can bequickly and convenientlyclamped merely by operating the electrically insulated hand operatingknob of the clamp. Additionally, the provision of a manual operatingknob for the clamp means that no tools are required to clamp the lead.

In one form of my instant invention the-terminal end ofan electricalterminal bushing isprovided with a hollow generally cup-shapedelectrical insulating member which is snugly seated at its wideopen endon said terminal end whereby'the terminal clamp at-said' terminal end issubstantially completely enclosed. The axis of States Patent 2 2,937,361Patented May 17, 1960 the clamp is generally perpendicularly disposedwith re spect to the axes of the cup-shaped member and bushing. Theclamp is provided with an electrically insulated operating knob whichextends through an aperture formed in a side wall of the cup-shaped.member, and another aperture. is formed in the opposite end of thecup-shaped member so that a lead which is generally parallel to the axisof said bushing can be. inserted into the lead receiving opening of theclamp and be clamped in the clamp. The cup-shaped member may be securedwith respect to the clamp and said terminal. end merely by theinterlocking. or abutting disposition of the knob and the peripheralportions of said side wall aperture with respect to each other. However,additional. securing means may also be used if so desired.

My invention will be better understood from the following descriptiontaken in connection with the accompanying drawing and its scope will bepointed out in the appended claims.

In the drawing Fig. 1 is a view in perspective of one form of myinvention. Fig. 2 is an enlarged broken away sectional view taken alongthe line 2 2 of Fig. 1. Fig. 3 is a sectional view along line 3--3 ofFig. 2, and Fig. 4 is a broken away sectional view along line 44 of Fig.3. Like reference numerals will bev used throughou the various figuresto indicate identical parts.

Referring now particularly to. Fig. 1, shown therein is. a verticallydisposed electrical terminal bushing 1 which is constructed fromporcelain or other electrical insulating material and has a plurality ofpetticoats formed thereon. Bushing 1 is mounted on a cover 2 of a maintank 3 of an electrical apparatus such as. a transformer. The. upper.terminalend of bushing 1 has a terminal clamp mounted thereon which. isprovided withan electrically insulated manual operating member or handknob 4. The terminal clamp is. probably best shown in Fig. 2, and theterminal clamp as well as the upper terminal end of bushingjl issubstantially completely enclosed by a hardrubber or other electricalinsulating material hollow member 5. Member 5' is generally cupshapedand' is inverted whereby its wide open end is snugly seated on.thefrusto-conical surface 6 of the upper petticoat of bushing 1. Theopposite or upper end of member 5 has a small aperture 7 formed thereinfor the passage of an electrical lead 8' therethrough which is clampedinthe terminal clamp. The lead 8 and the axes of member 5 and bushing 1are generally parallel to each other and vertically disposed whereas.the axis of the terminal clamp is generally horizontal and perpendicularto the lead' 8" and the axes cf'member 5 and bushing 1. An aperture 9is'formed in a side wall of mem. ber 5 for the knob 4; The aperture 9 isonly slightly, larger than a hollow cylindrical portion 10 of the knob 4so that projection of'portion 10 through aperture 9 results ininterlocking of" the member 5 with respect to the terminal clamp and theupper terminal end of bushing 1- with aminimumof looseness.

A wide variety of terminal clamps can be used'in my invention, and thespecifically illustrated. terminal clamp is claimed and described indetail in my'patent 2,740,100,

entitled Electrical Cable Clamp, issued March 27, 1956,.

opposite sides as well as opposite ends of the studli up to block. 11. v

The hollow cylindrical portion 10 of'knob 4 has an internally threadedcylindrical nut 14 of the like fixed "therein which threadablycooperates with stud 12 Also, stud 12 and nut 14 have provision for spinfree engagement therebetween by virtue of the fact that the threads onboth stud 12 and nut 14 are divided into two spaced threaded sectionsThe left-hand end of nut 14 is preferably integrally closed so that apin 15 can be securely fixed inside of nut 14 coincidental with the axisthereof. A spring 16 surrounds the pin 15 and is compressed between theleft-hand end of nut 14 and the left-hand end of a stem 17 of agenerally T-shaped clamping block.

The stem 17 has a notch 18 formed therein and the right-hand end of pin15 extends through the left-hand end of stem 17 into notch 18. Theright-hand end of pin 15 has an enlargement 19 formed thereon which issmaller than the notch 13 so that the pin 15 and T- shaped clampingblock have a lost motion connection therebetween.

In Fig. 2 the terminal clamp is shown in its fully tightened positionwhereby thelead 8 is clamped between a cross piece 20 of the T-shapedclamping block and the block 11. The cross piece 20 is abutting theright-hand end edge of nut '14 and the spring 16 has been compressed.Since the cross piece 2t abuts the right-hand end edge of nut 14 thespring 16 cannot be overcompressed. The spring 16 and the lost motionconnection between pin 15 and the T-shaped clamping block provide aspring follow up clamping action in the event the lead 8 becomes loosein the terminal clamp due to cold flow of the metallic conductor of lead8. That is, if the lead 8 tends to become loose with respect to thecross piece 20 and block 11 the spring 16 will urge the T-shapedclamping block in a right-hand direction to take up any slack in thelead connection.

In the fully clamped Fig. 2 position of the parts the T-shaped clampingblock and the pin 15 and spring 16 are disposed in the notch 13. Afterthe knob 4 is turned to loosen the terminal clamp the threaded sectionon the end of each of members 12 and 14 will become aligned with thenon-threaded portion of the other member. In this position of the devicean operator will know by the feel of knob 4 that the clamp is open.Further outward turning of knob 4 will engage the threaded sections onthe ends of members 12 and 14 with each other and ultimately result incomplete removal of the knob 4 and its attached parts from the stud 12.However, before this occurs the feel of knob 4 during spin freeengagement of the parts 12 and 14 will apprise the operator of the factthat the clamp is open whereby the danger of accidental disassembly ofthe clamp and falling parts is minimized.

The member is installed by removing the knob 4 and its attached partsfrom the stud 12. Then the member 5 is slipped over the block 11 andstud 12 so that the stud 12 is'aligned with aperture 9. Then the nut 14of knob 4 is engaged with stud 12. In the mounted position of member 5the aperture 7 is aligned with the notch 13 or the lead receivingopening of the clamp which is defined by the split stud 12 and thespaced cross piece 20 and block 11.

In some electrical installations a lightning arrester is mountedadjacent to the bushing terminal with an external spark gaptherebetween. For this purpose the member 5 may have a slot 21 formed inthe side thereof about 90 from the aperture 9. The slot 21 is shieldedby a generally U-shaped external bafiie 22 which may be an integral partof member 5. An electrode member 23 which is electrically connected tothe terminal clamp projects through the slot 21 into the baffle 22. Whenan external spark is established between electrode member 23 and anotherelectrode member of an adjacent lightning arrester there is a dangerthat the arc will play on the side Walls of the baffle 22 and corrodethe same if the electrode member 23 is not spaced sufiiciently from saidside walls. Therefore, a pair of small shouldered pertions 24 areintegrally or otherwise formed adjacent the side edges of slot 21 andalong the side walls of bafile 22. A small generally T-shaped clip ortab 25 which is fixed with respect to the terminal clamp and upperterminal end of bushing 1 has its cross piece projecting into the slot21. The opposite ends of said cross piece fit into the shoulders of theshouldered portions 24 whereby the member 5 is interlocked with respectto the terminal clamp and upper terminal end of bushing 1 independent ofprojection of the knob portion 10 through aperture 9 or the degree ofcloseness therebetween. Additionally, the opposite ends of the crosspiece of tab 25 extend laterally beyond opposite sides of the electrode23 and are disposed in abutting relationship with respect to the sidewalls of baffle 22 and the side edges of slot 21 whereby said side wallsand side edges and electrode 23 are amply spaced with respect to eachother.

While there has been shown and described a particular embodiment of theinvention, it will be obvious to those skilled in the art that changesand modifications may be made without departing from the invention, andtherefore it is intended by the appended claims to cover all suchchanges and modifications as fall within the true spirit and scope ofthe invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In an electrical bushing having a clamp mounted on one end thereof, ahollow generally cup-shaped electrical insulating material member seatedat its wide open end on said one end and substantially completelyenclosing said clamp therein, said clamp having an externally threadedmember which is disposed generally perpendicular to the axis of saidbushing and an electrically insulated nut on said threaded member forclamping an electrical lead in said clamp, said nut extending through anaperture formed in a side wall of said hollow member and having anelectrical insulating material hand knob at the outer end thereof whichis disposed outside of said hollow member, and another aperture formedin an opposite end of said hollow member, said another aperture and anelectrical lead receiving opening of said clamp being aligned withrespect to each other whereby an electrical lead which is clamped insaid clamp will be disposed generally parallel to the axis of saidbushing, and a slot formed in said side wall with a metallic electrodemember which is electrically connected to said clamp projecting intosaid slot in spaced relationship to the side edges thereof, and a tabwhich is fixed with respect to said clamp and bushing one end projectinginto said slot in abutting relationship with respect to said side edgesfor retaining said side edges and electrode member in spacedrelationship.

2. In an electrical bushing having a clamp mounted on one end thereof, ahollow generally cup-shaped electrical insulating material member seatedat its wide open end on said one end and substantially completelyenclosing said clamp therein, said clamp having an externally threadedmember which is disposed generally perpendicular to the axis of saidbushing and a nut on said threaded member for clamping an electricallead in said clamp, said nut having an electrical insulating materialhand knob which is disposed outside of said hollow member and extendsthrough an aperture formed in a side wall of said hollow member, andanother aperture formed in an opposite end of said hollow member whichis aligned with respect to an'electrical lead receiving opening of saidclamp whereby an electrical lead which is clamped in said clamp will bedisposed generally parallel to the axis of said bushing, and a slotformed in said side wall, said slot being shielded by electricalinsulating material external walls which extend along the side edges ofsaid slot, a metallic electrode member electrically connected to saidterminal clamp extending into said slot in spaced relationship to saidside edges and external walls, a pair of shoulders formed adjacent saidside edges, and a clip which is fixed with respect to said clamp andsaid bushing one end engaging said shoulders to fix said hollow memberwith respect to said clamp and said bushing one end and to retain saidelectrode member in spaced relation- 5 ship with respect to said sideedges and external walls.

516,341 Ayrton et a1. Mar. 13, 1894 6 Hill Oct. 29, 1935 Aime Mar. 11,1941 Joublanc Dec. 29, 1953 Lucas Aug. 16, 1955 Broverman Mar. 27, 1956FOREIGN PATENTS Great Britain Sept. 24, 1914

